Match the following columns and select the correct option.
| Microbe | Product |
|---|---|
| (a) Clostridium butylicum | (i) Cyclosporin-A |
| (b) Trichoderma polysporum | (ii) Butyric acid |
| (c) Monascus purpureus | (iii) Citric acid |
| (d) Aspergillus niger | (iv) Blood-cholesterol-lowering agent |